Buffy Silverman 
Can You Tell a Dolphin from a Porpoise? [PDF ebook] 

An animal with smooth, gray skin jumps from the ocean waves. Its tail waves up and down before it quickly dives again. Did you just see a dolphin? Or was it a porpoise? These animals look very similar, but they are different. Read this book to become an expert at telling these look-alikes apart!Learn the fascinating differences between similar animals in the Animal Look-Alikes series part of the Lightning Bolt Books collection. With high-energy designs, exciting photos, and fun text, Lightning Bolt Books bring nonfiction topics to life!